Brother-in-Law of Notorious French Jihadist Held after Syria Trip

The brother-in-law of Mohamed Merah, the Al-Qaida-inspired gunman who went on a killing spree in 2012 that shocked France, was arrested at a Paris airport Tuesday on suspicion of having joined jihadists in Syria.

The man -- the husband of Merah's sister Souad, who herself is believed to be in Algeria -- was detained at Orly airport near Paris along with two other people, interior ministry sources said.

All three were arrested in Turkey at the end of August and handed over to French authorities, the sources added.

The arrests came just a day after the radical Islamic State group, which controls large areas of Iraq and Syria, called on Muslims to kill citizens of countries taking part in the U.S.-led coalition against the jihadists, which includes France.

French authorities are particularly wary about nationals who have traveled to the two restive countries to wage jihad and may return to their home country to stage attacks.

Already in May, Interior Minister Bernard Cazeneuve had warned that Souad Merah, the sister of the gunman who killed three French soldiers and four Jews -- including three children -- in March 2012 in the southwestern city of Toulouse, had left France and may be fighting in Syria.

Mohamed Merah himself died after being shot by police following a prolonged stand-off at the apartment block where he lived.

It later emerged that he had visited Pakistan and Afghanistan prior to his attacks and had been on the radar of French intelligence, who had gravely underestimated the threat he posed.

His sister Souad left Toulouse in May for Barcelona, from where she took a flight to Istanbul and then another plane for the Turkish city of Gaziantep, near the Syrian border.

According to a source close to the case, she is currently in Algeria after having left Syria.

Among the two others who were held Tuesday was a 27-year-old man who had already been arrested in 2007 for being part of a network that recruited candidates for jihad in Iraq, an intelligence source said.

The third was a resident in the southern city of Albi where another jihadist network was dismantled over the summer.

According to Cazeneuve, around 930 French citizens or residents, including at least 60 women, are either actively engaged in jihad in Iraq and Syria or are planning to go.